The objective of this proposal is to establish a means of monitoring the specific immunocompetence of human mononuclear cells after trauma. The cooperative immune functions of Thymus derived cells (T cells), Accessory cells (A cells), and Bone marrow derived cells (B cells) will be assessed since each of these leukocyte subpopulations is involved in mediating different immune responses. T, A and B leukocyte immune cooperation are all required during generation of antigen stimulated antibody forming cells. Consequently, the in vitro generation of specific antibody forming cells (AFC) is used as the primary probe in our evaluations of immune leukocyte interactions after injury. A new method for inducing human peripheral blood leukocytes to produce specific AFC in vitro is described. We use this method to analyze immune leukocyte interactions of both normal individuals and trauma and surgery patients. As a prelude to evaluating human leukocyte immune status, we must separate normal human leukocytes into T, A and B cell subpopulations, verify the purity of the isolated subpopulations, and define the normal immune function of these leukocyte subpopulations in generation of AFC responses. Once we have established these parameters for normal A, T and B cell immune functions, the leukocytes from surgical patients with suspected immune dysfunctions will be separated into the same A, T and B subpopulations. These patient A, T and B subpopulations will then be examined for deviation from the established norml leukocyte immune interactions during the in vitro generation of specific AFC responses.